Renewable energy source cycle

                                                  Revision notes, what you should know

key: Highlighted on green and blue dark title
       Highlighted on light blue subtitle
       Highlighted on light green answers    

       Highlighted on yellow quetions

Classification and use of keys

B1a What do all living things do?

. Living things are called organisms.

. Organisms must do all of these things: Move, Reproduce, use their Senses,

Grow, Respire, Excrete waste and take in Nutrition.

. You can remember all seven of these using the phrase ‘MRS GREN’.

B1b How do scientists divide living things into groups?

. Dividing things into groups is called classification.

. Living things are divided into kingdoms. Members of the plant kingdom can

make their own food, animals cannot.

. Vertebrates are animals that have backbones.

B1c What are the differences between vertebrate groups?

. The main features of amphibians, birds, fish, mammals and reptiles.

. Each type of animal (or plant) is called a species.

B1d What are invertebrates?

. Invertebrates are animals without backbones.

. The main features of arthropods, echinoderms and molluscs.

What groups can arthropods be divided into?

. The arthropods are split into four smaller groups: arachnids, crustaceans,

insects, and centipedes and millipedes.

. The main features of these groups.

B1e What groups are plants divided into?

. The main features of mosses, ferns, conifers and flowering plants, and how

they reproduce.

. Plants make their own food using energy from the sun in a process called

photosynthesis.

Cells and their functions

B2a What are the differences between plant and animal cells?

. Animal cells have a nucleus, cytoplasm and a cell membrane.

. Plant cells also have a cell wall, a vacuole and chloroplasts.

. What all of these parts do.

How do we use a microscope?

. The main parts of a microscope and what they do.

B2b How can we look at cells?

. How to prepare a microscope slide.

B2c Why do cells have different shapes?

. Some cells are adapted to do special jobs.

. How ciliated epithelial cells, nerve cells and root hair cells are adapted.

. A group of the same sort of cells is called a tissue.

B2d What is an organ?

. Different tissues are grouped together to form organs.

. Each organ has a very important job.

What do human organs do?

. About all the organs on the next page, where they are and what they do.

What do plant organs do?

. About all the plant organs on this page where they are and what they do.

. Plants make their own food using photosynthesis.

. Photosynthesis needs light to work.

. Photosynthesis uses up water and carbon dioxide and makes sugar and

oxygen.

B2e How do organs work together?

. Cells group to form tissues. Tissues group to form organs. Organs group to

form organ systems. All of these make up a living thing – an organism.

. Water is lost by plants though their leaves. The organs in the breathing and

digestive systems.

Solutions and Indicators

C1a How do we know if something has dissolved?

. Some solids dissolve in water to make a solution. These solids are soluble.

. A solution contains a solute (solid) and a solvent (liquid).

. A solution is always transparent.

. Solids that do not dissolve are insoluble.

What is the difference between melting and dissolving?

. Solids can melt when they are heated. They change back when they cool

down.

. Dissolving occurs when a soluble solid mixes in with a liquid.

. Mass of solvent + mass of solute = mass of solution.

C1b How much solute can we dissolve?

. When no more solute can be dissolved in a solution, it is said to be saturated.

. The amount of solute that dissolves depends on the volume of solvent (e.g.

water) and its temperature.

How can we make things dissolve faster?

. You can make something dissolve more quickly by stirring it, by crushing it

into smaller pieces, or by heating the water.

C1c How can we remove ink or paint marks?

. Water is the most common solvent.

. Other liquids can also be used as solvents.

. Solutes which are insoluble in water may dissolve in other solvents.

C1d What is an indicator?

. Litmus is an indicator which is red in acids.

. Vinegar and fruit juices are acids.

What is an alkali?

. Litmus turns blue in alkalis.

. Alkalis can cancel out acids, making them neutral. We call this neutralisation.

. Some alkalis are dangerous.

C1e How can we make a better indicator?

. The strengths of acids and alkalis can be measured on the pH scale.

. pH numbers 1 to 6 are acids, 7 is neutral, and 8 to 14 are alkalis.

. You can find out the pH number using universal indicator.

Mixtures and separating techniques.

C2a How can we make use of everyday mixtures?

. A mixture is different materials mixed together.

. Examples of some useful things obtained from some everyday mixtures.

C2b How do we get clean water?

. Filtering can be used to separate solid particles which do not dissolve from

the liquid that is holding them.

. Filtering cannot be used to separate particles which dissolve in the liquid.

C2c Why doesn’t all water taste the same?

. Most water has small amounts of salt dissolved in it.

. If you evaporate the water the salt is left behind.

C2d How can we make pure water?

. Distillation is evaporation followed by condensation.

. What mixtures distillation can be used to separate.

C2e How can mixtures of dissolved solids be separated?

. What chromatography is, how it works and it is used for.

. How to make a chromatogram.

Particle Theory

C3a Why do different materials have different properties?

. Materials have different properties because they are made from particles

which are arranged in different ways, making a solid, liquid or gas.

. A solid can be melted into a liquid by heating it.

. A liquid can be frozen into a solid by cooling it.

. A gas can be condensed into a liquid by cooling it.

. The meanings of the words evaporating, condensation, freezing and melting.

. For any substance, the freezing point and melting point are the same.

C3b What is a solid?

. Solids are made up of particles that are very close together.

. Solids are difficult to squash, do not flow, have a fixed shape and volume, and

have a high density.

C3c Why do liquids flow?

. Liquids are made up of particles that are fairly close together.

. Liquids cannot be squashed, flow quite easily, and have a fixed volume but no

fixed shape.

. Although they are dense, liquids have a lower density than solids.

C3d How are gases different from solids and liquids?

. Gases are made up of particles that are well spread out.

. Gases are easy to squash, flow easily, have no fixed volume and no fixed

shape.

. Gases have a lower density than liquids.

C3e What is the difference between a solid, a liquid and a gas?

Changes of State

C4a What do we mean by the word ‘state’?

. The three states of matter and their properties.

. What boiling, evaporating and condensing mean.

C4b How can freezing make you hotter?

. What melting and freezing mean.

. All changes of state involve heat energy moving from one place to another.

How can freezing stop food and drinks going off?

. At room temperature, food goes off because bacteria grow and reproduce

quite quickly. This can cause food poisoning.

. Bacteria grow and reproduce more slowly at low temperatures.

C4c What happens to water when we boil it?

. When it is boiling, the temperature of the liquid stays the same.

. What bonds are and what happens to them when water is heated.

C4d What happens if we keep on diluting?

. All drinks contain water. Most also contain colourings and flavours.

. All substances are made up of tiny particles.

. What dilute and concentrated mean.

. The difference between an observation, a theory and a prediction.

C4e How do the smells of cooking spread from the kitchen?

. What diffusion is.

. Diffusion occurs because particles in a substance are always moving.

. Why diffusion is faster in gases than liquids.

Which energy sources rely on the Sun?

. The energy sources used in geothermal, tidal and nuclear power are the only

ones that do not depend on the Sun.

. The Sun is the original source of energy for most of our energy sources.

P4d How is energy wasted in energy changes?

. When energy is changed from one form to another, useless heat energy is

often produced.

P4e How can we use less of our non-renewable fuels?

. How heat loss can be reduced by using insulating materials containing

trapped air.

20 fundamentaly questions about chemistry

1. What is Chemistry?

2. What is a solution?

3. What is a mixture?

4. What is a soluble?

5. What is a solvent?

6. What means dissolve?

7. What means when a solution is clear?

8. What is a soluble problem?

9. What means when a solution is saturated?

10. How do we know when something has dissolved?

11. How much solute can we dissolve?

12. What is evaporation?

13. What is filtering?

14. What is condensation?

15. What is freezing?

16. What means stirring?

17. What is a liquid?

18. What is a solid?

19. What is a dissolvent?

20. Does salt dissolve in water?

Solutions

Solutions and Mixtures

Before we dive into solutions, let's separate solutions from other types of mixtures. Solutions are groups of molecules that are mixed up in a completely even distribution. Hmmm. Not the easiest way to say it. Scientists say that solutions are homogenous systems. Other types of mixtures can have a little higher concentration on one side of the liquid when compared to the other side. Solutions have an even concentration throughout the system. An example: Sugar in water vs. Sand in water. Sugar dissolves and is spread throughout the glass of water. The sand sinks to the bottom. The sugar-water could be considered a solution. The sand-water is a mixture.

Can Anything Be In Solution?

Pretty much. Solutions can be solids dissolved in liquids. They could also be gases dissolved in liquids (such as carbonated water). There can also be gases in other gases and liquids in liquids. If you mix things up and they stay at an even distribution, it is a solution. You probably won't find people making solid-solid solutions in front of you. They start off as solid/gas/liquid-liquid solutions and then harden at room temperature. Alloys with all types of metals are good examples of a solid solution at room temperature. A simple solution is basically two substances that are going to be combined. One of them is called the solute. A solute is the substance to be dissolved (sugar). The other is a solvent. The solvent is the one doing the dissolving (water). As a rule of thumb, there is usually more solvent than solute.

Making Solutions

So what happens? How do you make that solution? Mix the two liquids and stir. It's that simple. Science breaks it into three steps. When you read the steps, remember... Solute=Sugar, Solvent=Water, System=Glass.

1. The solute is placed in the solvent and the concentrated solute slowly breaks into pieces.
2. The molecules of the solvent begin to move out of the way and they make room for the molecules of the solute. Example: The water has to make room for the sugar molecules.
3. The solute and solvent interact with each other until the concentration of the two substances is equal throughout the system. The concentration of sugar in the water would be the same from a sample at the top, bottom, or middle of the glass.

Can Anything Change Solutions?

Sure. All sorts of things can change the concentrations of substances in solution. Scientists use the word solubility. Solubility is the ability of the solvent (water) to dissolve the solute (sugar). You may have already seen the effect of temperature in your classes. Usually when you heat up a solvent, it can dissolve more solid materials (sugar) and less gas (carbon dioxide). Next on the list of factors is pressure. When you increase the surrounding pressure, you can usually dissolve more gases in the liquid. Think about your soda can. They are able to keep the fizz inside because the contents of the can are under higher pressure. Last is the structure of the substances. Some things dissolve easier in one kind of substance than another. Sugar dissolves easily in water; oil does not. Water has a low solubility when it comes to oil.